Changes in Northern Hemisphere September sea ice extent as simulated by CMIP5 models over the 21st century under different emission scenarios (RCPs). Sea ice extent is defined as the total ocean area where sea ice concentration exceeds 15% and is calculated on the original model grids.
The solid curves show the 5-year running mean mean under the emission scenarios RCP2.6 (blue) and RCP8.5 (red) based on those models that most closely reproduce the climatological mean state and 1979 to 2012 trend of the Arctic sea ice and the shading denotes the uncertainty range. The mean and associated uncertainties averaged over 2081−2100 are given for all RCP scenarios as colored vertical bars.
For completeness, the CMIP5 multi-model mean for RCP2.6 and RCP8.5 is indicated with dotted lines.
The dashed line represents nearly ice-free conditions.
Adapted from Figure SPM7(b) in the Working Group I contribution to the IPCC Fifth Assessment Report.